An important enabler of interactions over the Internet is the notion of trust, for it allows access to services, information, and customers without having to resort to validating procedures that can increase the complexity of an exchange so as to make it impractical. That is one reason why reputations play an important role in deciding the level of trust in commercial exchanges, in setting the value of particular brands, and in deciding whom to consult for professional advice.
A problem with reputations is that the time scales for their buildup or decay can be very long compared to the typical times involved in exchanges between a provider and a customer. This is not a problem if enough transactions have taken place so that a reputation or brand name can be established and made known to all parties concerned. However, this is not always the case. Accordingly, in place of such a reputation or brand name, a number of trust management mechanisms for online environments have been proposed, ranging from the familiar reputation feedback methods used by eBay™, to the creation of trust records and model-based compliance tools.
For all of these proposed solutions, however, either history or repeated interactions with a customer or system typically are necessary in order to establish a level of trust. Unfortunately, in many cases, especially those involving one-time exchanges or new providers of services, the repeated interactions necessary to establish a reputation are not feasible. Indeed, there are many situations in online environments where no reputation is available, while a need remains for an assurance that a particular quality of service (QoS) will be provided within a single exchange. One example is where a customer might require access to a utility data center that promises a given QoS level, but the customer cannot determine for certain whether or not that level of service in fact will be provided.